This disclosure describes various embodiments of novel energy converters, such as electrical generators, that effectively promote oscillations induced by flowing fluids, and utilize the oscillations in generating electricity or other types of energy by converting energy present in fluid flows, such as airflows, water flows, tides, etc. In one aspect, an exemplary generator harnesses the kinetic energy of fluid flows by way of aeroelastic flutter induced along a tensioned membrane fixed at two or more points.
An exemplary energy converter includes at least one magnetic field generator, at least one electrical conductor, and at least one flexible membrane. Each flexible membrane has at least two fixed ends and vibrates when subject to a fluid flow. As used herein, the term “flexible membrane” as used herein refers to a flexible material capable of morphing into a large variety of determinate and indeterminate shapes in response to the action of an applied force.
According to one embodiment, the at least one magnetic field generator may be implemented as permanent magnets attached to, and move with, the membrane. For instance, one or more magnets are integrated into or onto either side or both sides of the oscillating membrane. The at least one electrical conductor is disposed in proximity to the membrane and the at least one magnetic field generator, and has a curved or contoured surface bending substantially toward the membrane. The electrical conductor may be implemented as a single piece or a combination of multiple sets of conductors, using electrical conducting materials, such as aluminum or copper coils, of various geometries. A variation of the arrangement of the magnets and the electrical conductors may be attaching or affixing the electrical conductors to the membrane, and suspending in proximity to corresponding magnetic field generators.
The flowing fluid induces a spontaneous instability in the tensioned membrane known as aeroelastic flutter, or simply “flutter”. The flutter of the membrane results in a high energy oscillation mode, with a reduced torsion oscillation near the magnets nearer the ends of the membrane. Additionally, vortices shedding may occur along the edges and surface of the membrane, in some cases enhancing the oscillation.
The vibration of the membrane induced by the fluid flow causes a relative movement between the at least one electrical conductor and the applied magnetic field. The relative movement causes a change in the strength of the magnetic field applied to the electrical conductor, which induces a current flowing in the conductor.
This electric generator operates at a variety of fluid flow speeds, including lower speeds than required for most turbine-based generators. Moreover, the cost of an exemplary generator of this disclosure is substantially lower than most other fluid-flow harvesting generators. The absence of physically grinding parts offers the possibility of long, quiet, maintenance-free operation. No leading bluff bodies are required to initiate or sustain oscillation, although they can be employed if desired.
Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only exemplary embodiments of the present disclosure are shown and described, simply by way of illustration of the best mode contemplated for carrying out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.